playtest mode

kiln-core/src/board.rs

@@ -24,6 +24,12 @@ use std::collections::{BTreeMap, HashMap};
 /// separate element palette or index indirection. Access cells with
 /// [`Board::get`] and [`Board::get_mut`] using `(x, y)` coordinates.
 /// Use [`Board::is_passable`] for collision checks.
+///
+/// `Board` derives [`Clone`] to support deep-copying a whole [`World`](crate::world::World)
+/// (see [`World::deep_clone`](crate::world::World::deep_clone)) — e.g. the editor's
+/// playtest runs a game against an isolated copy so play mutations never touch the
+/// boards being edited.
+#[derive(Clone)]
 pub struct Board {
     /// Human-readable name for this board, loaded from the map file and round-tripped on save.
     pub name: String,